Understanding the difference between antibodies and vaccines

The immune system is the body’s biological defence to keep us healthy.1 It detects and destroys pathogens such as viruses or bacteria1 and is very good at identifying and destroying infected or unhealthy cells. However, sometimes the body needs extra assistance to recognise or fight intruders such as viruses or bacteria.1

Scientific advances have made it possible to enhance the body’s ability to produce pathogen-fighting cells or provide them directly to an individual.2,3

What are monoclonal antibodies and how are they used?

Antibodies are Y-shaped molecules produced naturally by the body’s immune system.4 They recognise, bind to and neutralise specific viruses and other pathogens.4,5

Monoclonal antibodies are produced in a laboratory to mimic or enhance the immune system's response.4 For more than 30 years, monoclonal antibodies have been approved and used to treat numerous diseases such as severe asthma, rheumatoid arthritis, Crohn’s disease, multiple sclerosis, infectious diseases and some types of cancer.7 In the setting of infectious diseases, monoclonal antibodies have the potential to provide almost immediate effect, making them potentially suitable for use in disease prevention as well as treatment.3,8,9

How are vaccines different from monoclonal antibodies for infectious diseases?

Monoclonal antibodies are often made from pathogen-specific immune cells of people who have recovered from an infection.10 They are highly specific and can be designed to identify and attack a particular disease-causing organism.11 Many copies of the antibody can be made and are usually given as an intravenous (IV) infusion or in some cases an injection.4

Vaccines use inactivated virus or bacteria or part of them to stimulate the body’s own immune response, including antibodies that help to recognise and destroy infected cells.12 As the immune system forms its own memory, vaccines essentially prime the body to fight a future infection if the person is later exposed to that particular pathogen.2 Vaccines are used to prevent a person from getting very sick from a particular illness in the future; they do not treat the illness.2

What is the difference between active versus passive immunity?  

Vaccines are a type of active immunity.3 They require a healthy immune system and help jumpstart the body’s natural ability to produce infection-fighting cells.2

Monoclonal antibodies are a type of passive immunity.3 This means they are given directly to an individual to rapidly protect against or fight an illness rather than being produced by the body.3

How long does it take vaccines and monoclonal antibodies to work?  

The immune response to a vaccine starts within days and develops over a few weeks.2 While a vaccine will train the immune system to battle future infections, monoclonal antibodies have the potential to provide almost immediate effect, neutralising intruders.2,6

How long do the effects of vaccines and monoclonal antibodies last?  

Immunity from vaccines is typically long-lasting.3 Some vaccines may require multiple doses for continued protection.2

The duration of effect of a monoclonal antibody can vary and often needs to be administered numerous times throughout therapy.13 Scientists continue to develop new technologies to modify and enhance the duration of action of monoclonal antibodies. Antibodies can now be engineered to resist breakdown in cells.14 This can prolong the time they last in the circulation, increasing the amount of time the antibodies could protect against viruses and other pathogens.14-17 This may also lead to less frequent administration compared to traditional methods of engineering.14-17


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1. National Institutes of Health. Overview of the Immune System. Available at: https://www.niaid.nih.gov/research/immune-system-overview. [Last accessed: October 2021]

2. Centers for Disease Control and Prevention. Understanding How Vaccines Work. [Internet]. CDC.gov; 2018. Accessed from: https://www.cdc.gov/vaccines/hcp/conversations/understanding-vacc-work.html. [Last accessed: October 2021]

3. Centers for Disease Control and Prevention (CDC).Immunity types. [Online]. 2017 May 10. Available at: https://www.cdc.gov/vaccines/vac-gen/immunity-types.htm. [Last accessed: October 2021]

4. Lloyd EC, et al. Monoclonal antibodies for COVID-19. JAMA. 2021; 325 (10): 1015. doi:10.1001/jama.2021.1225.  

5. Zost, S.J., et al. Potently neutralizing and protective human antibodies against SARS-CoV-2. Nature; 2020. 584: 443–449. Doi: https://doi.org/10.1038/s41586-020-2548-6

6. Loo Y-M, et al. AZD7442 demonstrates prophylactic and therapeutic efficacy in non-human primates and extended half-life in humans. medRxiv. Cold Spring Harbor Laboratory Press; 2021 [preprint] Available from: https://www.medrxiv.org/content/10.1101/2021.08.30.21262666v1

7. Lu RM, et al. Development of therapeutic antibodies for the treatment of diseases. J Biomed Sci 2020; 27, 1. https://doi.org/10.1186/s12929-019-0592-z

8. Salazar, G., et al. Antibody therapies for the prevention and treatment of viral infections. npj Vaccines 2, 19 (2017). https://doi.org/10.1038/s41541-017-0019-3.

9. Griffin MP, et al; Nirsevimab Study Group. Single-Dose Nirsevimab for Prevention of RSV in Preterm Infants. N Engl J Med. 2020; 383 (5): 415-425. doi: 10.1056/NEJMoa1913556. Erratum in: N Engl J Med. 2020 Aug 13;383 (7): 698. PMID: 32726528.

10. Infectious Diseases Society of America. Immunomodulators. IDSociety.org [Internet]. Available at: https://www.idsociety.org/covid-19-real-time-learning-network/therapeutics-and-interventions/immunomodulators/. [Last accessed: October 2021]

11. American Cancer Society. Monoclonal antibodies and their side-effects. Available at: https://www.cancer.org/treatment/treatments-and-side-effects/treatment-types/immunotherapy/monoclonal-antibodies.html. [Last accessed: October 2021]

12. Centers for Disease Control and Prevention. Understanding how COVID-19 vaccines work [Internet]. CDC.gov; 2021. Available from: https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/how-they-work.html [Last accessed: October 2021]

13. Ovacik M, Lin K. Tutorial on Monoclonal Antibody Pharmacokinetics and Its Considerations in Early Development. Clin Transl Sci. 2018;11(6):540-552. doi:10.1111/cts.12567 [Last accessed: October 2021]

14. Robbie GJ, et al. A novel investigational Fc-modified humanized monoclonal antibody, motavizumab-YTE, has an extended half-life in healthy adults. Antimicrob Agents Chemother. 2013; 57 (12): 6147-53. [Last accessed: September 2021]

15. Griffin MP, et al. Safety, Tolerability, and Pharmacokinetics of MEDI8897, the Respiratory Syncytial Virus Prefusion F-Targeting Monoclonal Antibody with an Extended Half-Life, in Healthy Adults. Antimicrob Agents Chemother. 2017;61(3): e01714-16. 

16. Yu XQ, et al. Safety, Tolerability, and Pharmacokinetics of MEDI4893, an Investigational, Extended-Half-Life, Anti-Staphylococcus aureus Alpha-Toxin Human Monoclonal Antibody, in Healthy Adults. Antimicrob Agents Chemother. 2016; 61 (1): e01020-16. 

17. Domachowske JB, et al. Safety, Tolerability and Pharmacokinetics of MEDI8897, an Extended Half-life Single-dose Respiratory Syncytial Virus Prefusion F-targeting Monoclonal Antibody Administered as a Single Dose to Healthy Preterm Infants. Pediatr Infect Dis J. 2018;37(9): 886-892b.

Veeva ID: Z4-39810
Date of preparation: November 2021